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Cranial Nerves XI-X (Glossopharyngeal & Vagus Nerves) :

Cranial Nerves XI-X ( Glossopharyngeal & Vagus Nerves) By Dr. Jamela Elmedany Dr. Essam Eldin Salama

Objectives :

Objectives By the end of the lecture, the student will be able to: Define the deep origin of both Glossopharyngeal and Vagus Nerves. Locate the exit of each nerve from the brain stem. Describe the course and distribution of each nerve . List the branches of both nerves.


GLOSSOPHARYNGEAL (1X) CRANIAL NERVE It is principally a sensory nerve with preganglionic parasympathetic and few motor fibers. It has no real nucleus to itself . Instead it shares nuclei with VII and X.

Components of fibers & Deep origin :

Components of fibers & Deep origin GVE fibers : arise from inferior salivatory nucleus , relay in otic ganglion, the postganglionic fibers supply parotid gland. SVE fibers: originate from nucleus ambiguus , and supply stylopharygeus GVA fibers : visceral sensation from mucosa of posterior third of tongue, pharynx, auditory tube and tympanic cavity, and carotid sinus, end in nucleus of solitary tract. SVA fibers : arise from the cells of inferior ganglion, their central processes terminate in nucleus of solitary tract , the peripheral processes supply the taste buds on posterior third of tongue. NST NA ISN Otic G

Superficial attachment & Course:

Superficial attachment & Course It arises from the ventral aspect of the medulla by a linear series of small rootlets, in groove between olive and inferior cerebellar peduncle. It leaves the cranial cavity by passing through the jugular foramen in company with the Vagus , Accessory nerves and the Internal jugular vein .


COURSE It Passes forwards between I nternal jugular vein and E xternal carotid artery . Lies Deep to S tyloid process . Passes between external and internal carotid arteries at the posterior border of S tylopharyngeus then lateral to it. It Reaches the pharynx by passing between middle and inferior constrictor, deep to Hyoglossus , where it breaks into terminal branches.


GANGLIA It has two ganglia: Superior ganglion: S mall , with no branches. Inferior ganglion : Large and carries general sensations from pharynx, soft palate and fauces.


Communications The Inferior ganglion with the Superior C ervical sympathetic ganglion. The Superior ganglion with the Auricular B ranch of Vagus. The Trunk with the Facial nerve at the stylomastoid foramen


Branches. Tympanic: relays in the otic ganglion and gives secretomotor to the parotid gland Nerve to Stylopharyngeus muscle. Pharyngeal: to the mucosa of pharynx . Tonsillar. Lingual : carries sensory branches, general and special ( taste) from the posterior third of the tongue. Sensory branches from the carotid sinus and body ( pressoreceptors and chemoreceptors ).


Summary It is principally a sensory nerve with preganglionic parasympathetic and few motor fibers. It is attached to the brain stem by a linear series of small rootlets lateral to olive in rostral medulla. Its afferent fibers conveys: General sensation from : Pharynx, Post. 1/3 of the tongue, Eustachian tube, and middle ear. Taste sensation of pharynx and 1/3 of the tongue Chemoreseptors in carotid body and baroreseptors in carotid sinus. Motor to stylopharyngeus Preganglionic parasympathetic synapses in otic ganglion.


VAGUS (X) CRANIAL NERVE It is a mixed nerve. It is the longest and most widely distributed cranial nerve. It is distributed till the right 2/3 of the transverse colon. It contains: Afferent, Motor , and Parasympathytic fibers.

Components of fibers & Deep origin :

Components of fibers & Deep origin GVE fibers: originate from dorsal nucleus of vagus nerve, synapse in parasympathetic ganglion, short postganglionic fibers innervate cardiac muscles, smooth muscles and glands of viscera. SVE fibers: originate from nucleus ambiguus , to muscles of pharynx and larynx. GSA fibers: sensation from auricle, external acoustic meatus and cerebral dura mater, spinal tract of trigeminal. GVA fibers: carry impulse from viscera in neck, thoracic and abdominal cavity to nucleus of solitary tract.

Superficial attachment & Course:

Superficial attachment & Course Its rootlets exit from medulla between olive and inferior cerebellar peduncle. Leaves the skull through jugular foramen. It occupies the posterior aspect of the carotid sheath between the internal jugular vein laterally and the internal and common carotid arteries medially . It has two ganglia: Superior ganglion in the jugular foramen Inferior ganglion, just below the jugular foramen


Course It lies on the prevertebral muscles and fascia. Enters thorax through its inlet: Right Vagus descends in front of the subclavian artery. The Left Vagus descends between the left common carotid and subclavian arteries. Passes through the Superior Mediastinum .


Communications Superior ganglion with: Inferior ganglion of glossopharyngeal nerve, S uperior cervical sympathetic ganglion& F acial nerve. Inferior ganglion with: C ranial part of accessory nerve, H ypoglossal nerve, S uperior cervical sympathetic ganglion. 1 st cervical nerve.


Branches Meningeal : to the dura Auricular nerve: to the external acoustic meatus and tympanic membrane. Pharyngeal :to muscles and mucous membrane of the pharynx. To carotid body Superior Laryngeal : It divides into: (1) Internal Laryngeal : Supplies; the mucous membrane of the larynx as far as the vocal folds. (2) External Laryngeal : supplies the cricothyroid muscle. Recurrent Laryngea : supplies all the muscles of the larynx (except cricothyroid ). The mucous membrane below the vocal folds. The mucous membrane of the upper part of trachea. Cardiac .


Summary It is a mixed nerve. It contains afferent, motor , and parasympatheyic fibers. The afferent fibers convey information from: esophagus, tympanic membrane , external auditory meatus and part of chonca of the middle ear. Ending in trigeminal sensory nucleus . Chemoreseptors in aortic bodies and baroreseptors in aortic arch. Receptors from thoracic abdominal and viscera, end in nucleus solitarius. The motor fibers arise from ( nucleus ambiguus of medulla to innervate muscles of soft palate, pharynx, larynx, and upper part of esophagus. The parasympathetic fibers originate from dorsal motor nucleus of vagus in medulla distributed to cardiovascular, respiratory, and gastrointestinal systems.

How you can test the Glossopharyngeal & Vagus nerves?:

How you can test the Glossopharyngeal & Vagus nerves? The person is asked to swallow. The person is asked to say ‘ah-h-h’ to check the movements of palate and uvula. The ‘gag reflex’ is tested by touching the back of the throat by the tongue depressor. The person is asked to speak to check the voice for hoarseness.

Motor Neurones diseases :

Motor Neurones diseases 1. Lateral medullary syndrome: A degenerative disorder seen over 50 years mostly due to Thrombosis of the Inferior Cerebellar Artery. 2. Tumors compressing the cranial nerves in their exiting foramina from the cranium via the skull base Manifested by: Ipsilateral paralysis of the muscles of the Palate, Pharynx and Larynx. Ipsilateral loss of Taste from the Posterior Third Glossopharyngeal nerve lesion is characterized by : dysphonia , dysphagia and absence of the gag reflex. Vagus nerve damage ; causes hoarseness or loss of voice, impaired swallowing, GI dysfunction, blood pressure anomalies (with CN IX), If both are nerves are affected, it would be fatal.

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